drm/amdgpu: reinstate oland workaround for sclk

commit e11ddff68a7c455e63c4b46154a3e75c699a7b55 upstream.

Higher sclks seem to be unstable on some boards.

bug: https://bugs.freedesktop.org/show_bug.cgi?id=100222



Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>